please help with mac video question

I'm a novice user of imac.The computer came loaded with imovie but this software doesn't do HD output. I'm not sure whether it would be best for me to buy imovie HD or would you recommend some other software .I'm interested mainly in editing home videos captured with my HD Panasonic camcorder.And yes, my budget is limited. Thank you for your help.
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Berghof G.C.